I cannot speak for the High Fidelity development team; but I can only infer from my recent work in QML that the font issues you speak of will be resolved when the remaining QML::OverlayWindow modifications solidify.

There are many things you are concerned with; this should probably not worry you too much. I can speak for myself when I say that font-size in HMD is important, and with resolutions of a 4k monitor being roughly on par with respect to panel resolution, my recent QML UI experiments will yield desired results.